Browsing by Author "Selyanchyn, Roman"

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    Identification and quality assessment of beverages using a long period grating fibre-optic sensor modified with a mesoporous thin film
    (Elsevier, 2014-07-23) Korposh, Sergiy; Selyanchyn, Roman; James, Stephen; Tatam, Ralph; Lee, Seung-Woo
    In this study, an optical fibre long period grating (LPG) sensor functionalised with a mesoporous thin film was employed for the identification and quality assessment of beverages. The principle of the discrimination of beverages using an LPG sensor is based on the measurement of the change in refractive index of a sensitive film, induced by the binding of the chemical compounds present in the beverage. The sensitive film deposited onto the LPG consisted of poly(allylamine hydrochloride) (PAH) and silica nanospheres (SiO2 NPs) with diameters ranging from 40 nm to 50 nm. PAH imparts selectivity, while the SiO2 NPs endow the film with high porosity and enhanced sensitivity. In this study, five different types of beverages, red and white wines, brandy, nihonshyu (sake, a Japanese rice wine), and shochu (a Japanese distilled beverage), prepared via distillation and fermentation, were used to assess the capability of the sensor to identify the origin of the beverages. In addition, a selection of red wines was used to evaluate the use of the sensor in the assessment of the quality of beverages. The results obtained were benchmarked against those obtained using gas chromatography–mass spectrometry for the determination of volatile compounds contributing to the flavours of a set of red wines. Principal component analysis (PCA) was employed for data analysis. This approach enabled both quality assessment of beverages and identification of the methods and materials used for their preparation.
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    Porphyrin-nanoassembled fiber-optic gas sensor fabrication: Optimization of parameters for sensitive ammonia gas detection
    (Elsevier, 2017-11-09) Korposh, Sergiy; Kodaira, Suguru; Selyanchyn, Roman; Ledezma, Francisco H.; James, Stephen W.; Lee, Seung-Woo
    Highly sensitive fiber-optic ammonia gas sensors were fabricated via layer-by-layer deposition of poly(diallyldimethylammonium chloride) (PDDA) and tetrakis(4-sulfophenyl)porphine (TSPP) onto the surface of the core of a hard-clad multimode fiber that was stripped of its polymer cladding. The effects of film thickness, length of sensing area, and depth of evanescent wave penetration were investigated to clearly understand the sensor performance. The sensitivity of the fiber-optic sensor to ammonia was linear in the concentration range of 0.5–50 ppm and the response and recovery times were less than 3 min, with a limit of detection of 0.5 ppm, when a ten-cycle PDDA/TSPP film was assembled on the surface of the core along a 1 cm-long stripped section of the fiber. The sensor’s response towards ammonia was also checked under different relative humidity conditions and a simple statistical data treatment approach, principal component analysis, demonstrated the feasibility of ammonia sensing in environmental relative humidity ranging from dry 7% to highly saturated 80%. Penetration depths of the evanescent wave for the optimal sensor configuration were estimated to be 30 and 33 nm at wavelengths of 420 and 706 nm, which are in a good agreement with the thickness of the 10-cycle deposited film (ca. 30 nm).